have you tried running some form of fuel cleaner in the tank? Or maybe changing fuel filters every couple of weeks until it clears up. Seems to me that would be easier than replacing fuel lines. If you have an Amoco station near you their premium is clear, you could use that for a few tank fulls along with several filter changes as a short term test to see if it resolves your idle problems. It sounds like your car may have been in storage for a while with a low tank of fuel. Is this correct?